Photographic reversal process



Patented M... '14-, 1939 UNITED, STATES PATENT OF Fl CE man KodakCompany, ltoc poration of New Jersey Application September 3, Serial No.182,331

No Drawing.

. 10 Claims.

This invention relates to a photographic reversal process andparticularly to agents which fog the unexposed portions of a sensitivephotographic layer prior to reversal.

In making positive photographic images by reversal from negativephotographic images, it is customary tobleach or remove the metallicsilver image before fixing the photographic element and while sensitivesilver halide remains in the element, and then to re-expose thesensitive layer and develop a positive image in the originally unexposedportions of the element. Methods have been proposed for fogging thesensitive layer after the first development so that the second exposureis unnecessary and then developing a positive image in the usual way.Many of the methods, previously suggested for thispurpose wereundesirable for various reasons, among which were that some of thefogging agents-required the use. of special developers for formationofthe positive image with an attendant lime itation on the physicalproperties'pf the final positive image, while others tended to produce astain in the film or paper in which'the image was formed.

It is accordingly an object of the present invention to provide areversal process in which positive images may be produced on developmentwithout a second exposure. A further object is to provide a reversalprocess in, which an ordinary'developer may be used in the seconddevel-- especially the aromatic-ring -substituted derivatives. Specificcompounds which I have found suitable are semicarbazide, phenyhydrazine, acetyl phenyl hydrazine, hydrazino benzoic acid and naphthylhydrazine. The hydrazine may, therefore, be substituted with variousgroups, such as an aromatic ring of eitherthe benzene or the naphthaleneseries, or a carbamyl group, and these groups may themselves containsubstituent groups. The carbamyl group is NHzC0-, so that hydrazinesubstituted with this group would have the structural formulaNHzCO-NHNHflsemictirbMlde) The following is a specific example of onemethod of forming a reversed P s tive image according to m'yinventi'on.

A sensitive photographic element which may be aplate, film, or paper isexpo'sedto a subject K namely, that of about heater, N. 1., a corin theusual way and is then developed in a solution having the followingcomposition:

Water liter" .75 Sodium sulphite, desiccated grams 48.8 Hydroquinone d024.4 5 Boric a do 5.6 Potassium bromide do 2.6 Sodium hydr do 24.4 Waterliter 1 10 After development at F. the film or paper is treated in thefollowing solution at 65-70 F. for a sufilcient length of time to bleachand remove the silver image formed by development without afiectingthesilver halide: j 5

Water men- 1 Potassium bichromate grams.... 9.4 Sulfuric .acid(concentrated) cc. 12

The film or paper is then washed and im- 20 mersed in a clearing hathmade up of grams of sodium sulfite in 1 liter'of water. The film orpaper is then again washed and without being exposed to light isdeveloped for 30 seconds in a developer having the same composition asfor the first development, but having added thereto 10 grams ofsemicarbazide hydrochloride.

After development the film is again washed and dried although the fixingat this stage is not essential. 30

I have described my redeveloping solution as containing 10 grams ofsemicarbazide hydrochloride in 1 liter. However, the amount of hydrazinederivative used may-be varied widely, without departing from myinvention. 3

Although I have described above the addition of my fogging or nucleatingagent to the second developer, this compound mayalso be added 'to theclearing bath, if the clearing bath ismade alkaline. In this case thefogging agent is used 40 in the same concentration as in the developer,

10 grams per liter of solution. 4 v

It isto be understood that the above example is illustrative only andthat my invention is to' tuted with a group selected from aromatic ring5 and carbamyl groups, and developing a positive image in the film.

2. The method of a positive photographic image from a negative image ina photo- 5 graphic element without a second exposure to light, whichcomprises removing the negative image, treating the element in a bathcontaining a semi-carbazide as a nucleus-forming agent, and developing apositive image in the film. 3. The method of making a positivephotographic image from a negative image in a photographicv elementwithout a second exposure to light, which comprises removing thenegative image, treating the element in a bath containing a phenylhydrazine as a nucleus-formin solution of a hydrazine substituted with agroup selected from aromatic ring and carbamyl groups as anucleus-forming agent, and without exposing the element to light,developing a'positive image in the film.

5. The method of making a positiveph'otographic image by reversal froman element containing a visible negative image and a transparent,sensitive, positive image, which' comprises removing the negative image,subjecting the element in the absence or an exposing light, to theaction of an aqueous solution or a hydrazine suhstituted with a groupselected from aromatic ring and carbamyl groups and developing a visiblepositive image-in the element.

v 6. A photographic reversal process comprising v forming a silver imagein a gelatino-silver halide smut; No. 2,150,701,.

CERTIFICATE-OF comcrIo u,

emulsion layer, removing the silver image with- 10 out aiiecting theremaining silver halide, subjecting the layer to the action of anaqueous solution oi semi carbazide as anucleus-forming agent, anddeveloping a positive image in the layer. 15

8. A photographic reversal process comprising forming a silver image ina gelatino silver halide emulsion layer, removing the silver imagewithout aiieoting the remaining silver halide, subjecting the layer tothe action of an aqueous 20 solution of a phenyl hydrazine as anucleus-forming agent, and developing a positive image in the layer.

9. A photographic reversal process comprisin forming a silver image in agelatino-silver halide 25 emulsion layer, removing the silver imagewithout affecting the remaining silver halide," subtion of hydrzinobenzoic acid as a nucleusjecting the layer to the action of an aqueoussolution-oi hydrazine enzoic acid as a nucleusforming agent, andeveloping a positive image in the layer.

10. A photographic reversal process comprising forming a silver image ina gelatino-silver halide emulsion layer, removing the silver image 5without afiecting the remaining silver halide, subjecting the layer tothe action of an aqueous solution of acetyl phenyl hydrazine as anucleusforming agent, and developing a positive image in the layer. 7 40JOSEPH ,C. VILLE.

Lama ii, i939.

.iosnrn c. V ILL'E is hereby certified. that error appe ersin theprinted specification of the above" numbered patent .r'equt-ri:n5correction ee'follows': Page 2, second coma, "line 23, claim 9, f"an-ira e: the; syllable-{worms and. syllable ue r hydrzinofhenzoicdam-as a ma a, me that. the maid Letters Patent" should'be-read withthis oorre'ctlenftherein that the may cone for-n to any record remisesin tho-Patent i e.

si aecf m sealed this 18151116117 of i rn, a.- i). 19 9.

Henry Van Arsdale ietia congressmen on. ravines;

